This project is concerned with the evaluation and development of granulocyte transfusion therapy as a life-support procedure in the treatment of idiopathic and iatrogenic agranulocytosis. Methods of procurement of granulocytes from normal donors will be compared. The value of granulocytes in the treatment of existing bacterial infection in agranulocytic patients will be assessed. A protocol for a study of the value of granulocyte transfusions in prophylaxis against bacterial infection of agranulocytic patients will be implemented. Uninfected patients will be randomized to control and treated groups. These studies will be undertaken in patients receiving allogeneic marrow transplants as part of the treatment of leukemia or marrow aplasia.